Tonight I was going through my Instrument Procedues Handbook when I came across an MLS approach. I understand how the approach works and why it was killed off and everything, but I still have some questions. Was the equipment needed in the plane similiar to the standard VOR receiver with a glideslope and localizer? Also, can anybody provide a complete list of all operational MLS systems in the United States?

I think the only operational MLS systems are military. I've only seen them installed in military aircraft. I think they are used mostly on a temp basis. They can set one up at an airfield rather quickly I think. The system has a antenna, a receiver box and the ones I'm familiar with used the same radio control unit and flight director.

I know on some C-130s that I have worked on, the MLS consisted of 4 antennas, a receiver, associated wiring and relays. The processed signal was sent to the fight director mode selector switch so that the pilot could select it for display on his ADI. The MLS is still being installed in some tactical cargo aircraft.